Organic light-emitting diodes (OLEDs) with fascinating features, such as high image quality, large viewing angle, thin, and lightweight, and their compatibility with rollable, wearable, and stretchable technology, have gradually entered into our daily life as the most promising next-generation displays. As to the advancements of OLED technology, there is ongoing demand on developing highly efficient emitting materials with color variability, which plays a crucial role in governing optoelectronic properties of OLEDs. Following the first generation of traditional fluorescent emitters and the second generation of heavy-metal phosphorescent emitters, [1] thermally activated delayed fluorescence (TADF) materials have emerged in the past few years and have been regarded as the most promising third generation emitters. [2] Aside from their triplet exciton Solution-processable thermally activated delayed fluorescence (TADF) emitters have received tremendous attentions in recent years due to their intrinsic merits of theoretical 100% exciton harvesting capability and excellent compatibility to low-cost and easily scalable solution processes. Herein, a comprehensive review of solution-processable TADF emitters is presented, including small molecules, dendrimers, and polymers. Their molecular design, optoelectronic properties, and device performances are summarized, and specific emphasis is placed on the structure-property relationships of these emitters. This review not only offers a guideline for designing highly efficient TADF emitters compatible with solution-processed organic lightemitting diodes, but also paves further directions for the development of solution-processable TADF emitters.